Thread: Walbro Wa and Wt Questions

Got a problem I can't seem to solve. Working on a Craftsman Blower and a Ryobi Trimmer. Both have Walbro Carbs. I serviced them both and rebuilt the carbs, new filters, and primer bulbs.

My problem now is both flood and empty the fuel tank while sitting. The needle and seats are new and perfect and the float level is correct. In fact if I disconnect and plug the fuel inlet to the primer bulb the problems stops. Both primer bulbs seem to be working fine and the check valves seem to shut the fuel off when not being pushed. As soon as the temperature gets higher and the fuel expands a bit in the tank, it siphons off through the carb and empties the tank into the cylinder and muffler.

What would cause this, there seems to be no check valve in the carb to stop this from happening. Could I have gotten two bad primers? Like I said this never occurred in either until I serviced them, and disconnecting the line and plugging it from the tank to the primer stops it while leaving the fuel inlet line in place.

Both have Walbro Carbs. I serviced them both and rebuilt the carbs, new filters, and primer bulbs.

My problem now is both flood and empty the fuel tank while sitting. Like I said this never occurred in either until I serviced them

Thanks Dale

I hate to disagree with fixer, but you test most 2cycle carbs for proper needle seat operation with a small pressure tester. Most vents, vent or don't.
I would think more along the lines of improper needle lever height or improper placement of the diaphragm base gasket on top of the actual diaphragm gasket. When it should be the other way around. This will cause your flooding issue in most cases.

The reason I said it sounded like a vent problem is I have lost count of the number of time some one lost the fuel cap on a trimmer or such and replaced it with a cap from a bottle of pills or cleaner or some such thing just to have pressure to build up and over ride the carb seat and leak gas all over the place. Replace the fuel cap with what was meant to be on it and the leaking carb stopped.

MowerMedic77=Do not worry about disagreeing with me. I can be wrong about anything just like every one else. If I was right all the time I would be better off picking lottery numbers.

I tested both nedles as Walbro site states and they hold 71/2# of pressure. Also checked the vents on both units caps they are working fine. Even left the caps llose to see if they were not working under pressure etc. Both again worked fine.

Leaving the main fuel line connected with the primer line plugged off and no flooding also disproves the needle theory.

Diaphrams are also placed correctly on both carbs have been through them both three times trying to solve this one growl. I have the full diagrams from Walbro and no answers there either. Rebuilt probably 8 or more of these carbs this summer for friends and family from Church not one other problem just these two.

I sure hoped that someone on this site could give me better answers or solutions than what I have gotten here. I wish I had the money to just buy a carb when one acted up, but I am disabled and on a very fixed income. I tinker witht hese things for something to keep me occupied. I do not charge these people anything for my services as they are mostly part of my congregation at Church. All I ask of them is the cost of the parts I may need. Can't stay down al of the time, gotta have something to enjoy doing with your hands. Also it helps to keep my mind fresh and going too.

Here's the way I see it. All you responses were basically - everything is to Walbro spec. Everything checks out. We give you suggestions and you say that it all checks out. We all know it's in the carb. So just buy a new one and be done with it. You said that they pay you for parts. You'll have it repaired in 5 minutes with a new carb. Ask them for the $50.00 for the new carb. Your not valuing your time. It is worth something. Get that unit done and gone so you'll have the time to repair some more equipment.

I tested both nedles as Walbro site states and they hold 71/2# of pressure. Also checked the vents on both units caps they are working fine. Even left the caps llose to see if they were not working under pressure etc. Both again worked fine.

Leaving the main fuel line connected with the primer line plugged off and no flooding also disproves the needle theory.

Diaphrams are also placed correctly on both carbs have been through them both three times trying to solve this one growl. I have the full diagrams from Walbro and no answers there either. Rebuilt probably 8 or more of these carbs this summer for friends and family from Church not one other problem just these two.

Any other suggestions?
Thanks Dale

Ok well the only other time I ever had a carb give me this much trouble I had found something that the people at Walbro could notell me why it would matter but it did. The new needles sometimes have what looks like a silver coating on the rubber tip(protect ant?) I usually never bothered even cleaning it off before assembly. Until this one unit gave me this same issue, I cleaned that coating off and it stopped Now I Just alway clean that stuff off, I Had rebuilt lots of carbs and never bothered with it but now I put a little gas on a rag and wipe it off and compressed air any lint or crap from the tip.
From all your other responses you may have already done this but it was the last thing I could think of.